XML 16 R33.htm IDEA: XBRL DOCUMENT v3.3.0.814

Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Gross goodwill	$ 875,714	$ 512,060	$ 514,426
Goodwill	875,714	512,060
Translation adjustment	(910)	(2,366)
Apex
Goodwill [Roll Forward]
Gross goodwill	645,448	287,951	289,712
Translation adjustment	(963)	(1,761)
Oxford
Goodwill [Roll Forward]
Gross goodwill	230,266	224,109	$ 224,714
Translation adjustment	53	$ (605)
Creative Circle [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	358,460
Creative Circle [Member] | Apex
Goodwill [Roll Forward]
Goodwill, Acquired During Period	358,460
Creative Circle [Member] | Oxford
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
LabResource [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	6,104
LabResource [Member] | Apex
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
LabResource [Member] | Oxford
Goodwill [Roll Forward]
Goodwill, Acquired During Period	$ 6,104

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 50



-Paragraph 1



-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267



Reference 2: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 45



-Paragraph 1



-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (a)



-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (a,h)



-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_GoodwillRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 350



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (f)



-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillTranslationAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=asgn_ApexSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=asgn_OxfordSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=asgn_CreativeCircleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=asgn_LabResourceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: